- [Instructor] Let's say you've got two people
and one person has tuberculosis,
that's this person over here, I'll call him Person A,
and another person does not, this is Person B over here.
So what are the things that are gonna make Person A
more infectious?
What are the things that we need to think about
in terms of how likely it is that Person B
will actually get sick with TB?
Well there are a few things.
So we know that this person actually has to cough out
some TB particles, right?
They're gonna cough them out.
And that means that the strength of the cough,
so let's say they have a real good cough, like that,
versus a really weak kind of puny cough, like that,
is gonna matter.
And it turns out that the folks that have the strongest
cough are the adults.
So any adults in general, adults are gonna have
a much stronger cough than children.
So that means that adults are more infectious
than children.
So let me actually write that as my first key point.
And it turns out that's exactly right, that we see
that in terms of spreading TB it's the adults
that spread it much more than kids,
and definitely much more than infants.
Now a second point is that you need live bacteria, right?
This seems obvious, that of course you're not gonna get
anyone sick if you don't have live bacteria.
And the way to know that someone has live bacteria,
you can actually just take some of their sputum
or some of their mucus from their lungs
and look under a microscope and you would actually see
what we call a positive smear.
And that literally means you smear out the mucus
under a microscope and you look with the microscope
and you can literally see the TB bacteria.
You could also do a culture and see if you can
actually grow the bacteria.
So if you can see the bacteria or grow the bacteria,
that's a good indication that there is live
TB bacteria there, and that's obviously gonna make
the person more infectious as well.
And a third point is if you look in their lungs
and you see large cavities, sometimes you call that
cavitary disease, but let me just write cavity here.
You see a cavity there, and that cavity we know
is gonna be full of little TB bacteria.
Those cavities are classic for that.
And so whenever you see or think about cavities
I want you to remember that the folks that get cavities
are the secondary progressive disease folks.
Remember there's primary and there's secondary,
and it's the secondary progressive disease that causes
these cavities.
So these are the folks that are gonna be more infectious
because they're loaded with live TB bacteria.
So what are the things we can do to actually prevent
the spread of TB?
The first one is actually kind of obvious,
it's medication.
So we have medications that are really good for treating
tuberculosis, and one classic thing that we've done
is what we call directly observe therapy, DOT.
Directly observe therapy, and all that means is that
sometimes a physician or nurse will actually watch
a patient take their medication so that they don't forget
or sometimes people don't like to take their medications.
This is an easy way to make sure that someone's actually
taking their medications, and we call it DOT.
And so that's obviously gonna be helpful for killing off
the bacteria so we don't have to worry about live bacteria
anymore, and usually that happens in about two weeks,
after two weeks of medications, that usually kills off
the bacteria so you no longer have those positive smears
and positive cultures.
And also helps with symptoms, right?
So if you're not sick with TB, you may not be coughing
as much.
So that's another important thing to keep in mind.
What else would be important?
Well you could imagine, isolation, right?
Making sure that person is actually isolated.
So isolation is key.
And specifically you want to make sure that they're not
around any young people.
So definitely don't want them around anyone
under the age of four years, because of course
children are really, really susceptible to getting
very sick with TB, so you want to make sure that
they're away from young children.
And you want to keep them isolated at night.
So at night when they're sleeping,
I put a little "at" symbol,
but at night when they're sleeping, you want to make sure
that they're isolated, maybe sleeping in their own room.
So of course it's ideal if the person is completely
isolated, but of course that's not always practical
because they might be with their family or their children.
But you want to make sure that they're at least
away from children under four and at night
that they're sleeping alone.
Another thing is a surgical mask.
So a surgical mask is really good because
it helps prevent too much of the stuff
that's coming out of your mouth to enter the air,
it actually literally, let me just draw it for you,
it literally catches a lot of the stuff
and prevents it from entering the space around you.
So this is a mask, let's say a surgical mask.
It might hook up like this, maybe like that.
And what it does is it literally catches the stuff
that's coming out of the mouth and makes it ricochet
back in.
You can still breathe with a surgical mask on,
but it just kind of keeps the large particles,
maybe large droplets from leaving your mouth.
Now what if you're Person B?
What's one thing you could do if you're Person B?
Well one obvious trick is just standing further away.
You don't have to stand so close to Person A,
you could stand all the way back here.
And that's gonna make it less likely that you're
gonna get sick with TB.
So let me write that here as create space,
create space.
Now another key idea is, think about what happens
when someone passes gas, or there's a horrible smell
in a room.
What are you gonna do?
Usually people are gonna find the door,
maybe they'll open the door and let some air in.
This arrow indicates more air coming in.
Maybe there's a window here, they're gonna open the window,
let that breeze come in.
Basically do whatever you can to kind of dilute out
that horrible smell.
If there's a fan, maybe you'll try to turn on the fan
and get that spinning.
And if you can get the fan going, that's also gonna
move around air.
You're just trying to move around air to get
a dilution of that horrible smell.
Let me write it out.
Dilute.
And the idea here is you can just
literally do simple things.
You can open up doors and windows, we call that
natural, natural ventilation.
You can also turn on a fan to kind of move air around.
And you're just trying to dilute out that horrible
bacteria so that less of it is likely to enter your lungs.
Another thing you can do is actually put on
an air purifying respirator.
An air purifying respirator is actually a little bit
different than the surgical mask.
This one is actually gonna keep out
very tiny, tiny particles.
So unlike the surgical mask, which gets kind of
the large things and spit and, you know,
large particles, this one is actually gonna capture
very tiny particles, and it's actually not gonna allow them
into your breathing area, your airway.
So it's actually gonna make things bounce off, essentially,
or get caught inside the filter itself,
and it won't allow TB particles into your nose or mouth.
And a common one here, you might have heard of or seen,
is called the N95.
There are many other types as well, but that's one example
of an air purifying respirator.
Now a couple more things that you might see,
they're slightly more expensive,
but you might come across them or at least hear about them.
One is called ultraviolet, ultraviolet germicidal,
let's see if you can kind of guess how this works
or what it does.
Germicidal, -cidal means killing something.
Germicidal irradiation.
Irradiation.
And a lot of times people just shorten this whole thing
to UVGI.
They'll say, well UVGI was installed.
And what UVGI does, it literally takes ultraviolet light
and shines it out and actually,
if there are a couple of TB particles,
lets say one here and one here,
that UVGI, that irradiation kills that TB particle
and x's it out.
And so it's no longer alive and the folks in that room
are safe.
So then the final thing I want to talk about
is called a HEPA filter.
It's a filter, and if I was to draw the ceiling
it would look something like this.
Maybe it has some spot on the ceiling
where air is flowing in, and some spot
where air is flowing out.
Just erase these parts right here,
and I'll show you, let's say that air is coming in
this way, let's say three arrows,
and you've got air coming out this way,
you've got three arrows.
So in the middle, somewhere in this area,
you've got a filter.
And this filter is gonna catch TB particles.
And so we call it a high efficiency, efficiency,
particulate air filter, particulate air filter.
And no one wants to say all of this
because it's too long, and so just for short
again they say H-E-P-A, HEPA filter.
So a HEPA filter is gonna then catch some TB particles
that are gonna flow in, and they're gonna get stuck
in these filters, right?
And so coming out on the other side you have
nice, clean air because the TB particle
will not get through that filter.
And you could even take this a step further.
You could say, well how about if we did this?
And actually, instead of having all the air returned,
let's say we returned just part of it
and actually we allow some of the air to escape
outside of our room, right?
Well now you have a negative pressure in this room, right?
Because you have more air leaving the room
than is re-entering the room.
You have negative pressure, almost like a vacuum, right?
Because all this air is kind of going up
into the filter, and not as much is coming back out.
So this room becomes negative pressure,
this is kind of a vacuum in this room.
And especially if you do it right,
if you close off all these doors and you close these windows
then you're definitely creating a negative pressure.
And what that means is that now you can really protect
the area around, because you close off the door,
you close off the window, and now there's no way
that a TB particle can leave and go into the hallway,
because if there's a little bit of a gap underneath
this door, if that's the only crack in this room,
then the negative pressure is gonna make air flow
through that crack into the room instead of air
flowing out into the hallway.
So that's actually another key trick that they use
to prevent TB from spreading, is they'll create
a negative pressure where they pump air out,
which is what we showed here.
And then they'll seal off the whole room
and then the air from the hallway starts entering the room
and you can make sure that no TB particles are gonna get
out into the hallways and get people in the hallway sick.